core/fpdfapi/page/cpdf_annotcontext.cpp

// Copyright 2018 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#include "core/fpdfapi/page/cpdf_annotcontext.h"

#include <utility>

#include "core/fpdfapi/page/cpdf_form.h"
#include "core/fpdfapi/page/cpdf_page.h"
#include "core/fpdfapi/parser/cpdf_dictionary.h"
#include "core/fpdfapi/parser/cpdf_stream.h"
#include "core/fxcrt/check.h"

CPDF_AnnotContext::CPDF_AnnotContext(RetainPtr<CPDF_Dictionary> pAnnotDict,
                                     IPDF_Page* pPage)
    : annot_dict_(std::move(pAnnotDict)), page_(pPage) {
  DCHECK(annot_dict_);
  DCHECK(page_);
  DCHECK(page_->AsPDFPage());
}

CPDF_AnnotContext::~CPDF_AnnotContext() = default;

void CPDF_AnnotContext::SetForm(RetainPtr<CPDF_Stream> pStream) {
  CHECK(pStream);
  annot_form_ = std::make_unique<CPDF_Form>(
      page_->GetDocument(), page_->AsPDFPage()->GetMutableResources(), pStream);

  // The annotation expects the form content to be parsed with the identity
  // matrix (ignoring the matrix defined in the stream). To achieve this without
  // mutating the stream, pass the inverse of the stream's matrix as the parent
  // matrix during parsing. The parent matrix is applied to the stream's matrix,
  // effectively canceling out to the identity matrix.
  CFX_Matrix inverse_stream_matrix =
      pStream->GetDict()->GetMatrixFor("Matrix").GetInverse();
  annot_form_->ParseContent(nullptr, &inverse_stream_matrix, nullptr);
}